This invention relates generally to nebulizer jets of the type used, in conjunction with respirators, to create an aerosol consisting of air and a liquid, usually water and a medicinal substance intended for inhalation into a patient's lungs. More particularly, the invention relates to disposable nebulizer jets of this general type.
Basically, a nebulizer jet includes a small closed structure forming a nebulizer chamber. The chamber has a jet inlet port, a liquid inlet port, and an outlet port, the jet inlet port being axially aligned with the outlet port. A jet of air or other gas enters the chamber through the jet inlet port and draws a mixture of gas and liquid out through the outlet port. The liquid inlet port is connected by a tube to a supply of a liquid medicinal substance, which is drawn into the chamber by action of the jet flow. The nebulizer jet also includes a convex fractionating surface, located outside the chamber and in the flow from the outlet port. The fractionating surface breaks the impacting flow of gas and liquid into a fine aerosol. For optimal nebulization, the jet inlet port and the outlet port are axially aligned and the jet inlet port is substantially smaller in diameter than the outlet port.
Disposable plastic nebulizer jets prior to this invention have been produced either as sets of separately molded parts, which must then be assembled into working devices, or as one-piece moldings. For nebulizer jets consisting of multiple parts, production and packing costs tend to increase proportionately with the number of parts. In addition, the time taken to assemble a nebulizer jet of this type is relatively long, since improper assembly could easily cause misalignment of the jet inlet and outlet ports, and degradation of nebulizer performance.
The molding process by which one-piece nebulizer jets were produced prior to this invention was a cumbersome one in some respects, involving the extraction of a number of mold pins from a single molded part. Extraction of the pins leaves intersecting passages in the molded part, to serve as the nebulizer chamber and as the inlet and outlet ports. In order to form the intersecting passages, the mold pins must be extracted from the part in non-parallel directions, and are therefore, subject to rapid wear. Moreover, the resultant fluid passages can not always be formed accurately and without surface flaws. Extraction of the mold pins sometimes scars the interior walls of the nebulizer, leaving burrs and dents that hinder optimal nebulization. These problems have largely discouraged the manufacture of nebulizer jets of one-piece construction.
Accordingly, there has existed a definite need for a molded one-piece disposable nebulizer jet that is economical to produce and package, easy to assemble, and also meets the structural requirements for optimal nebulization. The present invention satisfies this need.